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Application of functional fillers in composites: Effects of fillers content on the mechanical properties
Krhut, Jiří ; Petruš, Josef (referee) ; Poláček, Petr (advisor)
This work deals with the application of selected types of fillers and monitoring their addition to the specific properties of the resulting composite material. The theoretical part of this work includes a general description of composite materials, and selected types of matrices, followed by a brief description of the characteristics of particulate composites and the effect of fillers on selected material properties. In the experimental part, samples of polyester resin were prepared to contain the given content of filler based on aluminium hydroxide (Al(OH)3), expanded glass, hollow glass microspheres, and fillers based on nitrogen and phosphorus compounds. Subsequently, the influence of the used fillers on the rheological properties, flammability of the material, on mechanical and thermomechanical properties was monitored. Flame test methods, bending test methods and dynamic mechanical analysis (DMA) were used to evaluate the samples. Finally, the measurement was supplemented by an analysis of fracture surfaces using a scanning electron microscope (SEM). The addition of additives improved the fire resistance of the prepared materials. The mechanical and thermomechanical properties of the prepared materials differed significantly depending on the applied fillers and their content.
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Influence of glass fiber degradation on the mechanical response of a polymer composite
Součková, Lenka ; Knob, Antonín (referee) ; Čech, Vladimír (advisor)
The bachelor thesis studies the effect of fiber degradation with commercial sizing on the flexural properties of polymer composite based on unsaturated polyester resin reinforced with long unidirectionally oriented glass fibers. Fibres of age 23, 61, 67, 112 and 135 months were used to prepare a series of composite samples. The mechanical properties of a composite containing 40.5% % vol of fiber were determined using a three-point bending test defined by ASTM D790-17 standard. From the obtained data, the flexural strength, the flexural modulus and the flexural strain were evaluated. It has been found that the degradation of the fibers and their sizing leads to a reduction in flexural strength. This was due to the reduction of adhesion between the fibers and the matrix, thus also the quality of the interface, which caused insufficient stress transfer from the matrix to the fibre. The resulting difference in strength of composites with fibers aged 23 and 135 months was 0,19 GPa with respect to the origin value of 1,17 GPa. The obtained values were used to assess the correlation between the flexural strength of the composite and the shear strength. Pearson's correlation coefficient set at 0,71 corresponds to a strong correlation. The effect of fiber degradation on the flexural modulus has not been demonstrated.
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Preparation and characterization of unsaturated bio-polyester resins
Žůrek, Michal ; Petrůj, Jaroslav (referee) ; Figalla, Silvestr (advisor)
The theoretical part of this work is devoted to the selection of suitable components for synthesis of a branched oligoester and their structural arrangement. Further, oligomers of lactic acid esterified with crotonic acid branched by erythritol or pentaerythritol are discussed. Crosslinking of prepared oligoesters is accomplished by free radical mechanism using vinyl acetate as reactive diluent and 2,2'-azo-bis-isobutyronitrile as initiator. Resin was cured by vinyl acetate in different mass ratios. Results show that there in an optimal ratio for curing between oligoester and reactive diluent. Using less vinyl acetate results in insufficient crosslink density or, on the contrary, using considerable excess of vinyl acetate causes rapid polymerization, that also results in lower density of crosslinking. The crosslink density was determined indirectly by extraction of the soluble part to acetone after curing and drying of the product.
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Plasma surface modification of glass fibers and its optimization
Širjovová, Veronika ; Knob, Antonín (referee) ; Čech, Vladimír (advisor)
Diploma thesis deals with glass fiber surface modification using plasma-enhanced chemical vapor deposition in order to prepare functional interface that enhances the properties of polymer composites. The effect of deposition conditions on shear strength was observed with respect to the chemical composition of the deposited film. Thin films were deposited on planar substrates and fibers using monomer tetravinylsilane in a mixture with oxygen at selected power of plasma discharge. Chemical composition of prepared material was analyzed by infrared spectroscopy. Planar substrate film adhesion was measured using the scratch test. The composite sample was prepared by embedding the surface modified fibers in unsaturated polyester resin, followed by the curing process. The cured composite sample underwent the short beam shear test.
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Technological analysis of the usability of new thermosetting materials for the construction of headlamps
Rašner, Martin ; Kolář, Michal (referee) ; Píška, Miroslav (advisor)
The diploma thesis presents the usability of a new thermosetting material BMC for the construction of a car headlight. In the theoretical part there are described headlights, basic characteristics and properties of plastics focussing on polymer composite materials and material testing. The practical part deals with the processing of test samples for mechanical testing by compression moulding and also with the production of real samples of reflectors and carrier frames by injection moulding. The evaluation is based on comparison of the results of the performed tests of alternative material and the currently used BMC TETRADUR TD 492/2 in HELLA Autotechnik Nova s.r.o. Basic physical-mechanical properties such as strength, stiffness, toughness and hardness are tested and monitored. The reflectors and carrier frames are assembled into the headlight and then tested according to legal and customers´ requirements for climate and vibration resistance and photometry.
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Mechanical response of glass fiber-reinforced polymer composite
Širjovová, Veronika ; Svěrák, Tomáš (referee) ; Čech, Vladimír (advisor)
The bachelor thesis is concerned with mechanical properties of glass fiber-reinforced polymer composites depending on the surface modification of fibers and the volume fraction of fibers in the composite. The tested samples in a form of composite beams were consisted of polyester matrix reinforced with long glass fibers without surface treatment (unsized) and with commercial sizing. Shear and flexural tests were employed to evaluate adhesion at the fiber-matrix interface. The theoretical part focuses on literary search for composites, their components (matrix, reinforcement, interphase) and methods of testing their mechanical properties. The experimental part describes used materials, procedures and methods. In the result part, an assessment of the influence of the given conditions on the shear and flexural strength of the composite is summarized.
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"Centrum" Department Store in Brno
Dvořáková, Zuzana ; Sznapková, Radka (referee) ; Vojtová, Lea (advisor)
The subject of the thesis is an architectural study of the reconstruction and extension of the "Centrum" department store in Brno. It is a dominant building designed by the famous czech architect Vladimir Karfík, which is located at the Urban Conservation Area Brno. Object wasn´t realized with the full extent of the original proposal, so in the project is planned a completion of it. The new solution respects the historical quality of Urban Conservation Area Brno with a concurrent view of the location on the lucrative land in the city center. The architectural concept is based on a return to the original idea of the architect and the addition of my own creative contribution within the extension of the new floors. Draft of the extension is intended so that the individual parts of an object communicate with each other, but they are easily recognizable as well. This idea was filled by both parts linked together visually by horizontal lines and ripple, which is used on balconies of the extension and behind the facade of the current building by shielding walls. However it is emphasized the contrast between an enclosed mass and a free-flowing space. The existing part of the building is used especialy as a leasable area of trade and services. On the upper floors there are areas of administration. Furthermore, there will be a restaurant and cafe with exhibition galleries and apartments are designed on the new added floors. The building is adapted to use by person with limited mobility. Newly added uses in the object will increase the attractiveness of the building and its surroundings.
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The influence of surface modification of glass fibers on mechanical response of the GF/polyester composite
Janeček, Pavel ; Richtera, Lukáš (referee) ; Čech, Vladimír (advisor)
The diploma thesis is aimed at an influence of surface modifications of fibrous reinforcements on mechanical properties at the fiber-matrix interface in fiber reinforced composites. Glass fibers were used as reinforcements and polyester resin was the matrix. The sample of composite consisted of polymer matrix in a form of cylindrical body placed on bundle of glass fibers. The design of the sample was constructed with respect to results of Finite Element Analysis (FEA). The tensile test using a materials testing machine (Zwick) was employed to evaluate adhesion at the fiber-matrix interface. Untreated glass fibers, fibers with commercial sizing, and fibers modified by deposition of plasma polymer film using Plasma-Enhanced Chemical Vapor Deposition (PECVD) at different deposition conditions were used for fabrication of composite samples. The fibers and composite samples were analyzed by Scanning Electron Microscopy (SEM) and Confocal Laser Scanning Microscopy (CLSM).
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Fiber reinforcements for polymer composites
Knob, Antonín ; Grégr, Jan (referee) ; Čech, Vladimír (advisor)
The bachelor thesis is concerned with an influence of surface modification of fibrous reinforcements on mechanical properties at the fiber-matrix interface in fiber-reinforced polymer composites. Polyester resin was used as a matrix, glass and carbon fibers were the reinforcements. The composite sample consisted of polymer matrix in a form of cylindrical body placed on a bundle of fibers. Untreated fibers and fibers with a commercial sizing were used for fabrication of composite samples. The tensile test using a materials testing machine (Zwick) was employed to evaluate adhesion at the fiber-matrix interface.
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Preparation of glass fiber/polyester composites
Horská, Pavlína ; Richtera, Lukáš (referee) ; Čech, Vladimír (advisor)
The bachelor thesis is aimed at an influence of surface modifications of fibrous reinforcements on mechanical properties at the fiber-matrix interface in fiber reinforced composites. Glass fibers were used as reinforcements and polyester resin was the matrix. The sample of composite consisted of polymer matrix in a form of cylindrical body placed on a bundle of glass fibers. The tensile test using a materials testing machine (Zwick) was employed to evaluate adhesion at the fiber-matrix interface. Untreated glass fibers and fibers with commercial sizing were used for fabrication of composite samples.
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